The effect of colistin resistance and other predictors on fatality among patients with bloodstream infections due to Klebsiella pneumoniae in an OXA-48 dominant region

Abstract

Background: the aim of this study was to determine the effect of colistin resistance and other predictors on fatality among patients with Klebsiella pneumoniae bloodstream infections (Kp-BSI) and to describe the effect of amikacin and tigecycline on the outcome in an OXA-48 dominant country. Method: This was a retrospective study performed among patients >16 years of age in a tertiary hospital with 465 beds. All cases had ≥1 positive blood culture for K. pneumoniae 48 h after admission. Results: among 210 patients with Kp-BSI, the 30-day mortality rate after isolation of the microorganism was 58%. The rate of carbapenem resistance was higher (64% vs. 38%, p < 0.001) and the colistin minimum inhibitory concentration (MIC) was elevated (7 vs. 4, p < 0.029) among the patients who died. Among the colistin-resistant K. pneumoniae, the rates of OXA-48, ST101, and NDM-1 were 78%, 67%, and 35%, respectively. Amikacin was added to the treatment of 13 patients with carbapenem and colistin-resistant Kp-BSI and 77% survived (p < 0.001). Tigecycline was added to the treatment of 24 patients with carbapenem and colistin-resistant Kp-BSI, and the 30-day mortality rate was 71% (p = 0.576). In the multivariate analysis, carbapenem resistance (odds ratio (OR) 5.2, 95% confidence interval (CI) 2.47–10.9, p < 0.001) and increasing APACHE II score (OR 1.19, 95% CI 1.12–1.26, p < 0.001) were significantly associated with 30-day mortality. The addition of amikacin to the treatment regimen (OR 0.05, 95% CI 0.01–0.23, p < 0.001) was significantly beneficial. Conclusions: Carbapenem resistance, increasing MIC of colistin, and the lungs as the source of the infection were significantly associated with 30-day mortality. The empirical use of combined active aminoglycosides was found to be beneficial in the treatment of colistin-resistant K. pneumoniae infections.